Cardiac myxoma is the most common primary cardiac tumor. Most cardiac myxomas are located in the left atrium, and LV myxomas are quite rare[8]. Unlike myxomas, cardiac fibromas usually arise in the LV free wall[9].
Their early diagnosis is difficult since the symptoms and signs may be nonspecific, and symptomatic patients may present with a wide range of symptoms, which are determined by tumor location, size, and embolization tendency[10]. Pain, palpitations, episodes of syncope, systemic embolization and its complications are the main symptoms of LV myxomas[11]. In our case, the patient only presented with chest tightness and palpitations, and without other special symptoms.
Myxomas are not typically detected during physical examinations or in laboratory tests. Echocardiography, CT and magnetic resonance imaging (MRI) are the imaging modality enabling an accurate myxoma diagnosis[2]. The typical echocardiographic features of myxoma present as a solitary, heterogenous, slightly mobile, spherical mass attached to the surface of the endocardium, with a wide pedicle. What is more, internal hypoechoic areas, spot-like echogenic foci and lobular surface protrusions can be sometimes seen in myxomas[12, 13]. Cardiac fibroma always manifested as a homogeneous, solid, firm or rubbery, solitary mass, with a size range from 2 to 10 cm[4, 7]. They may display well circumscribed or infiltrating margins, and are usually located on one of the LV free walls[4]. Compared with myocardium in LV contrast-enhanced echocardiography, more contrast media was observed in the myxoma mass, only scattered and dotted contrast agent was present in the fibroma mass as it is mainly composed predominantly of collagen in adults [7, 14, 15].
In non-enhanced and contrast-enhanced CT, myxoma usually present as a heterogeneously low attenuated mass in the heart chamber with a smooth, irregular or villous surface, and heterogeneous enhancement was observed[16, 17]. Cardiac CT often demonstrates a homogeneous low density mass partial calcifications in fibromas whereas there was no imaging of contrast agent within it[18, 19]. The findings of echocardiography and CT of this case suggestive of a cardiac fibroma at imaging level.
Pathology is the gold standard for diagnosing heart tumors. Macroscopically, cardiac myxoma typically present as a single, pedunculated, fragile, and irregular shaped lesion with an intact capsule, whereas cardiac fibroma is solitary, circumscribed, firm, gray-white, partially calcified neoplasms without a capsule[20]. Histologically, cardiac myxoma is characterized by irregular or star shaped cells loosely dispersed within a mucoid ground substance[21]. However, cardiac fibroma is composed predominantly of collagen in adults [7].In our case, the surgical specimen, which is gray-white, firm, polyp-like, and composed by irregular tumor cells surrounded with voids and scattered with interstitial sparseness, is similar to cardiac fibroma at macroscopical level, but confirmed the cardiac myxoma at histological level.
Surgery is one of the most effective treatments for cardiac myxoma. And a complete surgical resection is highly recommended as the recurrence of cardiac myxoma may be caused by incomplete tumor removal[22]. Furthermore, regular follow-up with TTE is necessary to detect possible recurrences of this kind of cardiac tumor. In the 3-year follow-up, our patient had no recurrence of the tumor.
In conclusion, LV myxomas mimicking fibroma makes diagnosis difficult, and pathology is the gold standard for the diagnosis of myxoma. Complete surgical resection is the first choice to treat LV myxomas.